Working on a video, when all of a sudden it says my "files (being imported from an SD card) cannot be found". I close the Program and check my SD card, to find that all the footage that I was using in Premiere Pro had been swiped off of the card. Gone. It was wedding footage that I did not have backed up and can't reshoot. Has this happened to anyone else or what went wrong? Anything I can do? HELP.

You will need to seek out a program to let you undelete files from your card to try and recover them. Note: Try. It is not guaranteed to recover them all.

You learn a lot from your mistakes.

When starting a premiere project, first copy the entire contents (not just the video files) of your media card(s) into folder(s) on a hard drive, using windows File Explorer or Mac Finder, remove the memory card from the computer, put it somewhere safe and do not touch it until editing is 100% complete. Start premiere, set it up correctly according to the type of video your camera shot and then import the video files into premiere via media browser.